Heliscomyidae is a
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of
extinct rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...
s from the mid-
Tertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
of
North America related to
pocket gopher
Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...
s (family
Geomyidae) and
kangaroo rat
Kangaroo rats, small mostly nocturnal rodents of genus ''Dipodomys'', are native to arid areas of western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed t ...
s and their relatives (family
Heteromyidae
Heteromyidae is a family of rodents consisting of kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within th ...
). The family contains four genera, ''
Apletotomeus'', ''
Heliscomys'', ''
Passaliscomys'', and ''
Tylionomys'' (Korth et al., 1991; Korth and Eaton, 2004; Korth and Branciforte, 2007). McKenna and Bell (1997) placed the first two genera in
synonymy
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...
, with ''Heliscomys'' the senior synonym.
Characteristics
Heliscomyids are distinguished from other
geomyoid rodents by several characteristics of the
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
including fusion of three
cranial , elongation of the
incisive foramina
In the human mouth, the incisive foramen (also known as: "''anterior palatine foramen''", or "''nasopalatine foramen''") is the opening of the incisive canals on the hard palate immediately behind the incisor teeth. It gives passage to blood vesse ...
, and an unusual position of the
mental foramen
The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels.
Structure
The ...
(Korth et al., 1991).
Taxonomy
Heliscomyidae is a member of the
clade Geomyoidea, a group of rodents that also includes the families †Eomyidae, †Florentiamyidae, Heteromyidae, and Geomyidae. The following cladogram showing interrelationships among geomyoid families follows Korth et al. (1991):
References
*Korth, W.W. and C. Branciforte, 2007. Geomyoid rodents (Mammalia) from the Ridgeview Local Fauna, early-early Arikareean (late Oligocene) of western Nebraska. ''Annals of Carnegie Museum'' 76(3):177-201.
*Korth, W.W. and J.G. Eaton, 2004. Rodents and a marsupial (Mammalia) from the Duchesnean (Eocene) Turtle Basin Local Fauna, Sevier Plateau, Utah. ''Bulletin of Carnegie Museum of Natural History'' 36(1):109-119.
*Korth, W.W., J.H. Wahlert, and R.J. Emry, 1991. A new species of ''Heliscomys'' and recognition of the family Heliscomyidae (Geomyoidea: Rodentia) ''Journal of Vertebrate Paleontology'' 11(2):247-256.
*McKenna, Malcolm C., and Bell, Susan K. 1997. ''Classification of Mammals Above the Species Level.'' Columbia University Press, New York, 631 pp.
Geomyoid rodents
Prehistoric rodent families
Eocene first appearances
Miocene extinctions
{{geomyidae-stub